Means for preventing electrical interference



fiMayZD, 1924. 1,494,382 v R. B. sHANcK MEANS FOR PREVENTING ELECTRICAL4INTERFERENGE H Film may-27', 1921 CROSS-f/RE 3 NEUTRAL/ZIN@ f 1Q 5?hl/@ch 3513 Qu @Hoz-11mg v Patented Mey 2d, i924.

PATE? @Fidih ROY B. SHANCK, OF FLUSHING, NEW YORK, ASSIGNOR TO' AMERICANTLEPI-IONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

MEANS FOR PREVENTING ELECTRICAL INTERFERENCE.

Application led May 27, 1921.

To r/.ZZ whom t 77mg/ 0071067171:

Be it known that l, ROY B. SHANGK, residing at Flushing, in the countyot Queens and State ot New York, have invented certain Improvements inMeans for Preventing Electrical Interference, of which the following isa specification.

This invention relates to means for preventinof electrical interferencebetween siO'e kspectively.

na-ling circuits and specially to an arrangement for preventing thatform of interference between telegraph circuits which may be termedreceiving-end cross-tire.

ln the operation of telegraph signaling circuits it is well known thatwhen impulses are transmitted over one telegraph circuit an interferingcurrent will be set up in other circuits paralleling the first circuitdue to the mutual admittance between the circuit over which the impulsesare being transmitted, a-nd the circuits paralleling the same. Thisinterfering current will cause a disturbance in the terminal apparatusat both ends of the circuit in which the current is produced. Thedisturbance which is set up in the terminal apparatus oit said othercircuit which is located in the same station in which is also locatedthe terminal apparatus from which the impulses are being sent over theiirst mentioned circuit, may be termed sending-end cross-lire. Thedisturbance which is set up in the terminal apparatus oi' said othercircuit which is located in the same station in which is also locatedthe receiving apparatus of the said first mentioned circuit, may betermed receivingeend cross-tire. Sending-end crosstire has beensuccessfully neutralized in circuits by connecting a condenser betweenthe artificial lines of the duplex circuits.

It is the objectot this invention to provide a circuit arrangement forsubstantially neutralizing the receiving-end' cross-lire withoutincreasing` the sending-end cross-fire such as has resulted :trom theuse of arrangements heretotore designed for this purpose. v

Other and further objects of this invention will be apparent from thefollowing description when read in connection with the attached drawingshowing one Jform of embodiment of the invention.

Serial No. 473,118.

In the drawing, 1 and 2 represent two telegraph signaling circuits whichhave associated therewith the terminal circuits A and C respectively atstation X and B and D respectively at station Y. The opposite. ends ofthe line 1 are connected with one of the windings of the bridge coils 3and 4 respectively to the apeXes of which are connected the terminalcircuits A and B re- Across the outer terminals ot the bridge coils 3and 4 are connected the polar relays 5 and 6 respectively. The balancingnetworks ALl and ALL2 are connected with one winding of the bridge coils3 and 4 respectively to balance the line 1 connected with the said otherwinding of the said coils.

The terminal circuit at A comprises a pole changer 7 and an auxiliaryrelay 8 which are controlled by current from the. battery 9 by theoperation of the key 10. Batteries 11 and 12 are connected with thecontacts of the armatures of the pole changer 7 and the auxiliary relayS. Since opposite poles of these batteries are grounded. current ofopposite polarity will be applied to the two contacts of the polechanger and ot the auxiliary relay. The armature of the pole changer 7is connected with the apex of the bridge coil 8 and the armature of theauxiliary relay 8 is connected through the condenser 13 and resistance'14 with the apex of the bridge coil 23, associated with the line 2.

The terminal circuit B, located at station Y at the opposite end of line1, comprises a pole changer' 15 and an auxiliary relay 16, akkey 17 anda source of current 1S tor energizing the said pole changer andauxiliary relay. Batteries 1 9 and 20 arearranged to apply current ofopposite polarities to the armature of the pole changer and also to thearmature of the auxiliary relay. The armature of the pole changer isconnected with the apex of the bridge coil 4, and the arma ture of theauxiliary relay 1G is connected through condenser 21 and resistance 22to the apex of the bridge coil 24, connected with the line 2.

Bridged across the ends of the windings of the bridge coils 23 and 24are the polar` relays 25 and 26 respectively. These coilsA also haveassociated with them the artificial lines AL3 and AL, which are adaptedto balance the line 2. The terminal circuit C, which is similar tocircuits A and B, comprises pole changer 27 and an auxiliary relay 29controlled by current from the battery 3l by means of the key 32.Batteries 33 and 84 are adapted for connection with the armatures ot thepole changer and the auxiliary relay. Similarly circuit D comprises thepole changer 28 and the auxiliary relay 30, Which are controlled bycurrent from the battery 85 by means ot the key 36. Batteries 37 and 88are adapted for connection with the armatures of the pole changer andthe auxiliary relay respectively. The armatures of pole changers 2T and28 are connected with the apexes of bridge coils 23 and 24erespectively, and the armatures of the auxiliary relays #29 and 30 areconnected through condensers and resistances with the apexes of thebridge coils 3 and a respectively.

It will be seen that all of the tern'iiual circuits are structurallyidentical and that the terminal circuits at the same end of each lineare so arranged that the armature ot the auxiliary relay oteac-hterminal circuit is connected with the apex of the coil oit the otherline circuit. The admittance between the two parallel lines l and 2 isrepresented by the condenser C1 shown in the drawing as bridged acrossthe said lines at their mid points. It is to be understood, of' course,that such representation is purely symbolic since such capacity isnormally uniformly distributed throughout the length ot the parallelconductors.

Having in mind the foregoing description Ot the signaling system inywhich this inve-ntion is embodied, the invention can be more clearlyunderstood 'from thefollowing description of the inode ot operation oithe system: Let it be assumed that telegraphie impulses are beingtransmitted from station X to station Y over line l andthat at the sametime no impulses are being transmitted over line 2 in either directionbetween said station. It the signaling key l0 of circuit A, which isconnected with line l, is closed, the pole changer 7 and the auxiliaryrelay 8 will be energized, thereby causing their respective armatures tomove to their leithand contacts thus applying a` negative impulsethrough the armature of the pole changer to the apex ot the coil 8associated with line l and a positive impulse from battery l2 throughthe armature ot' relay 8 to the apex of coil'23 associa-ted with line 2.The negative signaling impulse applied to line l will tend to causeinterfering current to flow in line 2 in the directions represented bythe vwavy arrows. The effect of this inter-tering impulse upon thereceiving apbaratas 26 atrstation Y lwill be neutralized by the impulseolz opposite polarity represented by the dotted arrows which wasimpressed upon line 2 by the operation of the auxiliary relay 8simultaneously with the impression oi the signaling impulse upon line l.This neutralizing impulse will be transmitted over line 2 towards thedistant end, and, although it may be reduced in magnitude by suchtransmission, it will be capable of neutralizing the resultantinterfering impulse which is also attenuated by transmission. ltis` ofcourse, to be understood that the interfering impulse produced in line 2by the signaling impulse impressed upon lineI l is not as great as theoriginal signa-ling impulse and, conserpiently, the neutralizing impulseimpressed upon line 2 by the operation ot the auxiliary relay associatedwith circuit need be only of sutcient magnitude to neutralize theinterfering impulse. The directions of liow oi' the signaling,interfering and neutralizing currents vfor the circuit conditions justde* scribed are as shown by the various arrows upon the drawing.

lt the signaling lrey l0 is opened ilfor the 'transmission ot a signalot opposite cl1aracter between station X and station Y, the armaturesoit the pole changer 7 and the relay S will move to their right-handcontacts, thereby applying a positive impulse :trom battery l2 throughthe armature of the pole changerto the apex of the coil connected withthe line l anda negative yimpulse from vbattery ll through the larmatureof the auxiliary relay S to t-he apex ot the coil connected with line 2.The positive impulse which is produced in line 2 bythe impression of thepositive impulse to line l will be lneutralized by the negative impulseoit corresponding magnitude applied to line 2 by the operation ot theauxiliary relay 8. The directions of tlow oil the signal-ing,interfering and neutralizing currents tor the circuit conditions justdescribed will -be opposite to that represented by the arrows upon thedrawing. ly careful adjustment the interfering impulses may be substaintially neutralized, and the receiving apparatus 26 associated with theend ot `line 2 at station Y, where sigi'ials are Vbeing `received overline l, will not be affected by the cross-lire between line l and line2. It will also be seen than since the neutralizing impulses applied tothe line under crossre are directed to the apex of the` coil connectedwith the said line` no detrimental eitect will be produced in Vthereceiving apparatus, such as 25, connected with thesaid line.

In like manner it will be seen that it signals are transmitted tromstation Y to station X over line l and line is idle as hereto tore. thepolar relay 25 connected with line 2 and located at stationX will not bealiected by interfering impulses produced in line 2 by the transmissionof signaling impulses over line l.

Let it now be assumedthat signals are being transmitted simultaneouslyover lines l and 2 from station X to station Y. When key l() associatedWith the terminal circuit A is closed', the pole changer T and the auX-iliary relay 8 will be energized, and in consequence there will beimpressed upon line l a negative impulse and upon line 2 a positiveimpulse which will serve to neutralize the interfering impulse producedin line 2 by the transmission of the signal over line l. 'When key 32 isclosed, pole changer 27 and the auxiliaryfrelay 29 will be energized,and in consequence a negative signaling impulse will be impressed uponline 2 and the positive neutralizing impulse upon line l, Which willserve to neutralize the interfering impulse produced in line l by theimpression of the signaling impulse upon line 2. Accordingly, thereceiving apparatus 6 and Q6 connected With lines l and 2 respectivelyare rendered substantially free from the effect of cross-fire, althoughthey Will respond in the usual Way to the transmission of the signalingimpulse over their respective lines.

Although this invention has been shown as applied to two line circuitsonly, it is not thus limited, but is equally applicable to a systememploying a greater number of line circuits. Furthermore, the inventionis not limited to the particular form of circuit arrangement hereindisclosed, since it might be embodied in other and differentarrangements which will suggest themselves to those familiar With theart. The essence of this invention consists in the method and means forneutralizing receiving-end cross-lire by applying to the circuitsexposed to crosstire a neutralizing impulse simultaneous with theapplication of a signaling impulse over another circuit, the polarity ofthe neutralizing impulse being opposite that of the signaling impulseand of such magnitude as to substantially equal the impulse produced inthe exposed circuits by the signaling impulse transmitted over the saidother circuit.

It Will be seen from the foregoing description that my inventiondiscloses simple and effective means for protecting parallel telegraphcircuits against receiving-end interference. Furthermore since thecondensers C3 and C4, which are connected between the artificial linesides of each end of the circuits, are adapted to substantiallyneutralize sending-end interference, the effect of both the sending-endand the receiving-end interfering currents may be substantially reducedand the circuits rendered substantially free frominterference by meansof the arrangement herein disclosed.

Although this invention has been described as embodied in a particularform and arrangement of parts, it is to be understood that it is capableof embodiment in other forms and arrangements Without departing from thespirit and scope of the appended claims. l

What is claimed is:

l. In a telegraph signaling system comprising a plurality of adjacentcircuits, the method of reducing receiving-end cross-fire between saidadjacent circuits when signaling impulses are impressed upon one of saidadjacent circuits which consists in impressing uponthe other of saidadjacent circuits impulses of a character adapted to neutralize theinterfering impulses produced at the distant receiving station thereofby the transmission of signaling impulses over one of the said circuits.

9.. In a telegraph signaling system comprising a plurality of adjacentcircuits, the method of reducing receiving-end cross-lire between saidadjacent circuits, which consists'in impressing upon one of saidadjacent circuits an impulse of opposite polarity to the signalingimpulse impressed upon. the other ofsaid adjacent circuits. j

3. In a telegraph signaling system comprising a plurality of adjacentcircuits, the method for reducing receiving-end.cross-fire betweensaid-adjacent circuits which consists in impressing a signaling impulseupon one of said circuits, and in simultaneously impressing an impulseof opposite polarity upon each of the other of said adjacent circuits.

4. In a telegraph signaling system comprising a plurality of adjacentcircuits, the method for reducing receiving-end cross-fire between saidadjacent circuits which consists in impressinga signaling impulse uponone of said circuits, impressing an impulse of opposite polarity uponother of said circuits, and in reversing the polarity of the source ofcurrent connected with the latter of said circuits Whenever the polarityof the source connected with the former circuit is reversed'.

5. In a telegraph signaling system, the combination with two adjacentline circuits, of sending circuits and receiving circuits individual toeach line circuit, each sending circuit being characterized by means forapplying a signaling impulse to its respective line circuit, and also toapply simultaneouslyl an impulse of opposite polarity to the other ofsaid adjacent circuits whereby receivingend cross-lire in the said othercircuits may be reduced.

6. In a telegraph signaling system, the combination With two linecircuits of polar duplex terminal circuits individual to each of saidline circuits, each of said terminal circuits being adapted to apply asignaling impulse to the apex of the bridge coil of its respective linecircuit, and also to apply loo simultaneously to the -apex of the coilof lthe ,otlierfline circuitan impulse having a polarity opposite tothat vof the .signaling impulse.

7. In a telegraph signaling system, the combination with a line circuitoi a second line circuit, a .sending circuitand a receiving circuitindividual/,to each ofk said line circuits, means yassociated with eachof. said sending circuits to apply a signaling impulse to -itsrespective line circuit dand to control the simultaneousapplicationitothe `other of said line circuits of, an impulse lof Opposite .polarityto the signaling impulse.

S. In a telegraph signaling system, the

combination -Witha plurality of line circuits, each hinting a bridgecoil, a balancingvnetwork and a polar relay connected .at .each end, aterminal circuit individual to each line circuit comprising a kpolechanger controlledby a key adapted to apply, signaling impulses ofpredetermined polarity to the said line circuit, andanauxiliary'relayalso controlled by the said key adapted to apply 'l tokeach of said other line circuits impulses of polarities v.opposite tothe signaling yimpulses applied to the line circuit with which aparticular terminal circuit may be connected.

9. n ,zi telegraph signaling system, the

3f combination Witha line circuit of asecond line circuit, a terminalcircuit individual to Lacasse teach line circuit comprisingsources ofcurrent of opposite` polarity `and vmeans for ,applying simultaneouslyimpulses of opposite polarity to each of said line circuits.

10.111 a telegraph signalingsystem, the combination with a line circuitof a second line circuit, Ia-terminal circuit individualto each linecircuit comprising sources of cui'- rent of opposite polarity, means forapplying .a signaling impulse of predetermined .polarity totherespective line circuits and current of'opposite polarity, andanauxiliary relay, the circuit being so arranged that theiarniature of thepole changer is connect- .ed with the line circuitfto which the saidterminal circuit is. ,individual and the varmature `yof theauxiliaryrelay is connected with the other adjacent line circuits.

In `testimony whereof, I have signed my name tothisfspecication this24th day of May, 1921.

:ROY B. SHANC'K.

